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Preventable anesthesia mishaps: a study of human factors*
  1. Jeffrey B Cooper,
  2. Ronald S Newbower,
  3. Charlene D Long,
  4. Bucknam McPeek1
  1. 1Laboratories of the Bioengineering Unit, Department of Anaesthesia, Harvard Medical School at the Massachusetts General Hospital, Boston, Massachusetts 02114, USA


    A modified critical-incident analysis technique was used in a retrospective examination of the characteristics of human error and equipment failure in anesthetic practice. The objective was to uncover patterns of frequently occurring incidents that are in need of careful prospective investigation. Forty seven interviews were conducted with staff and resident anesthesiologists at one urban teaching institution, and descriptions of 359 preventable incidents were obtained. Twenty three categories of details from these descriptions were subjected to computer-aided analysis for trends and patterns. Most of the preventable incidents involved human error (82%), with breathing-circuit disconnections, inadvertent changes in gas flow, and drug syringe errors being frequent problems. Overt equipment failures constituted only 14% of the total number of preventable incidents, but equipment design was indictable in many categories of human error, as were inadequate experience and insufficient familiarity with equipment or with the specific surgical procedure. Other factors frequently associated with incidents were inadequate communication among personnel, haste or lack of precaution, and distraction. Results from multi-hospital studies based on the methodology developed could be used for more objective determination of priorities and planning of specific investments for decreasing the risk associated with anesthesia.

    • anaesthesia
    • safety
    • accidents
    • equipment failure

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    • * As intended by Flanagan, the originator of the technique, the term "critical incident" refers to an occurrence that is significant or pivotal, in either a desirable or an undesirable way. For this study, we chose to examine only those incidents that had potentially undesirable consequences.

    • Many complications of anesthesia are not "preventable" given the finite limits of medical knowledge. The incidents considered here are those where the anesthetist clearly failed to follow accepted practice or where a piece of equipment ceased to function normally. When doubt existed about preventability, the incident was excluded.

    • * *The range of reported occurrences per interview was 2 to 27. The range of critical incidents extracted frorn these occurrences was 1 to 15.

    • * We view the number of incidents retrieved in each interview as a sample representing an unknown fraction of the number actually experienced by the interviewee. Thus, only relative frequencies can be discussed.

    • * Preliminary results from a second hospital show similarities in most categories of incidents, but differ strikingly on the issue of relief. As many incidents were induced by the exchange of personnel as were discovered or corrected as a result of the relief process. It appears that transferences of responsibility for a case from one anesthetist to another in the two hospitals differ. Thus, providing relief may be a good practice, but only when carried out with careful transfer of information and authority.

    • Supported in part by a grant from the National Institute of General Medical Sciences, GM 15904.

    • * This is a reprint of a paper that appeared in Anesthesiology, 1978, Volume 49, pages 399–406.